# Application Development Overview<a name="EN-US_TOPIC_0000001162242674"></a>
# Application Development Overview
The application development documents provide reference for you to develop applications using the APIs provided by OpenHarmony. The documents provided walk you through how to use JavaScript \(JS\) APIs to develop applications on the standard system.
The application development documents provide reference for you to develop applications using the APIs provided by OpenHarmony. They walk you through how to use JavaScript APIs to develop applications on the standard system.
To get a glimpse of the basic methods for developing applications, see [Basics](quick-start/start-overview.md). For details about the API list and references, see [Reference](reference/apis/js-apis-featureAbility.md).
The documents are carefully organized as follows:
To better understand frequently used modules, see the development guidelines for [Ability](ability/fa-brief.md), [UI](ui/arkui-overview.md), [Media](media/Readme-EN.md), etc.
### Getting Started
For details about the principles and basic information of each subsystem, see the README file in **docs/en/readme**.
[Here](quick-start/start-overview.md) you'll learn how to quickly get started with OpenHarmony application development.
Browse the documents on the instructions for quickly building your first application and the basics about OpenHarmony applications.
Check out the development fundamentals, which comprise descriptions of the package structure configuration file for OpenHarmony applications and the instructions for use of resource files.
### Development
To facilitate your application development, we provide development guidelines for key features.
First thing first, familiarize yourself with the two cornerstone frameworks in OpenHarmony applications:
DevEco Studio is a high-performance integrated development environment (IDE) recommended for developing OpenHarmony applications.
[Here](https://developer.harmonyos.com/en/docs/documentation/doc-guides/ohos-deveco-studio-overview-0000001263280421) you can learn everything about DevEco Studio, including how to use this tool to create a project and sign, debug, and run an application.
### Hands-On Tutorials
To make you better understand how functions work together and jumpstart your application development projects, we provide stripped-down, real-world [samples](https://gitee.com/openharmony/app_samples/blob/master/README.md).
### API References
API references encompass all components and APIs available in OpenHarmony, helping you use and integrate APIs more effectively.
They are organized as follows:
-[Component Reference (JavaScript-based Web-like Development Paradigm)](reference/arkui-js/js-components-common-attributes.md)
-[Component Reference (TypeScript-based Declarative Development Paradigm)](reference/arkui-ts/ts-universal-events-click.md)
> The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.
Implements the extension context. This module is inherited from **Context**.
> The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.
Provides extension running information.
## Usage
The extension running information is obtained through an **abilityManager** instance.
```
import abilitymanager from '@ohos.application.abilityManager';
> The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.
Implements the context that provides the capabilities and APIs of **FormExtension**. This class is inherited from **ExtensionContext**.
> The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.
Implements the context that provides the capabilities and APIs of **ServiceExtension**. This class is inherited from **ExtensionContext**.
| want | [Want](js-apis-featureAbility.md#Want) | Yes| Information about the ability to connect to, such as the ability name and bundle name.|
| options | [ConnectOptions](#connectoptions) | Yes| Callback used to return the information indicating that the connection is successful, interrupted, or failed.|
**Return value**
| Type| Description|
| -------- | -------- |
| number | A number, based on which the connection will be interrupted.|
